Chronometer?
an instrument for measuring time very accurately. For a Swiss watch to be called a chronometer it must meet very high standards set by the C.O.S.C. (Controle Officiel Suisse des Chronometres). The requirements are 15 days and nights at 5 different positions and temperature changes. The Organization of Swiss Watch Manufacturers definition as of 1951: “A Chronometer is a precision watch which is regulated in various positions and at different temperatures and has received a certificate to that effect”.
